It has long been known that bandsaws for sawing thick metal should preferably have teeth with different pitch distances, to avoid vibration and corrugation of the cut sides. For reasons related to production and maintenance of the sawblade, the teeth are produced in recurrent groups, with variations of pitch distances, setting and height within the groups.
It is also known that in general the vibration damping and the cutting ability are best if each of the recurrent groups consists of a large number of teeth, often seven or more teeth.
In the production of the sawblade the first operation is milling simultaneously the whole tooth group with the desired pitch distance and height. Very long recurrent groups will then require large milling cutters, heavy milling machinery and very strong clamping of the sawblade.
It is also known from FIGS. 15a-c of U.S. Pat. No. 4,827,822 that a longer group for the total variation of height, pitch and setting van be provided by combining one shorter variation of height and pitch with another short but different variation of setting. In the cited instance, it is known to combine a three member height and pitch variation with two member setting variation to produce a three times two=six member total period. This example can be extended to larger numbers, the total period being the height and pitch variation period times the setting variation period. Having a long total period is also previously known to be beneficial to reduce the vibrations, but doing it as shown in Amada '822 makes it difficult to do the setting with desired precision unless the setting is done either one tooth at a time, which is a slow method, or for the whole total period which may need large expensive setting anvils and hammers. It would be advantageous if the setting could be done with anvils and hammers covering just the length of the setting variation, but because in Amada '822 the height difference and pitch distance between the two teeth to be set at a time would be different each time, the precision would be insufficient and the saw efficiency would suffer.